Pellet Rolling ~~ Part 1.

Jump to latest Follow Reply
G

Guest

Guest
There are five parts to this series. They will be linked here at the end of today's editing session:

PART ONE

PART TWO

PART THREE

PART FOUR

PART FIVE



Rifle: HW-98, 0.20

Optic: SWFA 10

Test Pellet: H&N Baracuda at about 688 fps

Distance: 25 meters.

First I shot five different pellets to determine which one shot the worst. That fell to the H&N Baracudas.

I shot 30 shots to create each of the following aggregate targets. I then scored the groups and removed the five worst shots from each of the data sets. I did that because I was testing outside and wanted to minimize wind drift errors. I maintained three wind flags between myself and the target at 25 meters.

I first shot the group directly from the tin. Here it is.

TIN.1627091218.jpg


The most important measurement here is the mean radius. This is the measurement which best describes the performance of the sample set. Observe these pellets represent the average performance for that tin of pellets.

I used my printer to make a Yrrah Pellet Roller and a catch box with seven cells in it. This let me capture pellets quickly and sort them by rolling into several groups at one pass. When rolling pellets they fall into a pattern which is a normal curve (bell curve).. My catch box was made with seven cells and so it was easy to select all the pellets which fell into the middle of the curve. All of the pellets fell into five of the cells in the catch box. I selected ONLY pellets from the CENTER box with no concern for which pellets might actually shoot best in the rifle. I just wanted to see if I could improve the performance of the pellets by rolling them in this manner.

Here is that target.

TINROLL1.1627091656.jpg


Now then that left me with the pellets which fell "above" the middle group and the pellets which fell "below" he middle group. I lumped them together with the expectation that the resulting group would indeed be worse than the average. That expectation may or may not have been a good theory. This is the result.

Here is that group.

TINROLL-1.1627091955.jpg


From these tests I conclude that the Yrrah-Roll test, invented by user Yrrah on the GTA forum a few years ago offers a substantial improvement in accuracy by simply selecting pellets which tend to shoot closer to the same point from a batch of random pellets. The pellets which fall into the same slot in the catch box shoot to the same point of impact on the target.

EDIT: At this point the above conclusion was not warranted by this data. The the data does not show a significant improvement in accuracy. It suggests an improvement but certainly does not conclusively confirm it. I have redone the test indoors and started another thread (Part 2) which will be linked at the top of this thread.

Aim Small 😊
 
  • Like
Reactions: JungleShooter and mmahoney
Proof of if it works should REQUIRE a comparison of accuracy and poi shifts of the groups you sorted against each other, and against those sorted simply by appearance and weight, as is done by pretty much all compettive shooters. Just rolling into groups doesn’t prove the worthiness of doing it.

Some of us were rolling pellets for awhile back in the eighties, but it didnt seem to offer a worthwhile on-target result and the practice was abandoned,

LD 


 
Upvote 0
Proof of if it works should REQUIRE a comparison of accuracy and poi shifts of the groups you sorted against each other, and against those sorted simply by appearance and weight, as is done by pretty much all compettive shooters. Just rolling into groups doesn’t prove the worthiness of doing it.

Some of us were rolling pellets for awhile back in the eighties, but it didnt seem to offer a worthwhile on-target result and the practice was abandoned,

LD
Click to expand...

I was not testing the efficacy of any other means of classification. All I was trying to discover was whether I could show that rolling can be used to select pellets which tend to fly to the same point. So no, proof doesn't require anything except that rolling them actually does have an impact upon the POI and how they group. That's it. If rolling them does sort them by group size then it follows that it "works". Mean radius + standard deviation is a reasonable metric because it is heavily dependent upon the dispersion of shots within the group. Lots of shots close to the same point and you get a small SD and MR. Shots scattered all over the same sized group will give you a larger SD and larger MR.

The results tend to indicate that I can do that. It will take more shooting to show that with the kind of certainty a serious bench rest shooter would want. The biggest problem I have is managing shooting conditions so that I can get a meaningful result. At 25 meters it doesn't take much variability in the wind to ruin the test results. If I recall correctly Ted figured that out a couple of years ago at EBR =)

What I think I need to do at this point is test to see if each set of pellets sorted tends to shoot to a different point of impact and/or produces a smaller than average group. It will mean sorting and shooting for a couple of days to collect the raw data. Then a couple to process it.

Wanted to EDIT this in at this point in the thread:

Wind drift for a ONE mile per hour wind the pellet I am using at 25 meters shows as (full value) 0.12 inches (just over 3mm). A half value wind makes that 1.5mm approximately. Clearly testing with any air movement at all will introduce a variability which must be accounted. When you are shooting out of doors it is literally impossible for even the very best shooter to compensate for that 3mm unless the wind blows from exactly the same direction all the time. You if you get a 3 o'clock to 6 o'clock randomly switching 2 to 5 mph wind you have to compensate dynamically for anything from 6mm to 15mm at any moment.

The point I am trying to make is that this is a really tough problem that requires either a really large data set and some good number crunching or something like @Therealld s indoor range. Sounds like a beautiful setup.
 
Upvote 0
The benefits of pellet sorting (weighting, rolling) become more apparent at longer distances. Fractional grain weight-differences will result ibn measurable vertical drops at (for example) 100 yards, Try Chairgun set to 100 yards and plug in various minimum and maximum weights that one would normally find within the same pellet can.

Rolling helps detect deformed skirts or heads or non-uniform pellet dimensions which could affect twist-rates, etc. I think that with heavily choked barrels this may not be much of a opportunity for improvement, because it tends to "form" the pellet more uniformly to shape/size before it exists the barrel.

Yrrah (aka Harry) is still a member of this forum as well, but has not posted for a quite while. Would be great if he would chime in also about his experiments on pellet rolling. By the way, Yrrah may seem old-school but he has contributed numerous inputs to FX in their pioneering designs and also to JSB with their pellet designs.
 
Upvote 0
I thank fe7565 and boscoebrea for their positive comments. ... I think CORNPONE is on the right track to find objective support (or otherwise) for my system. He has made a good start with his approach already. . .... please enjoy your objective testing and experimenting CORNPONE. ... Best regards to all, Harry (Yrrah in Australia). Am 84 yrs now, have had my two Virus jabs with no problems; and am still experimenting and enjoying all my shooting and sharing on a more limited one-on-one basis with likeminded friends widely separated in countries around our world.
 
  • Like
Reactions: OldSpook
Upvote 0
Yrrah, great to hear from you and glad to know you are active, healthy, and engaged. Your posts were always educational and thought provoking. 

Our hobby has changed leaps and bounds during the last few years thanks to the internet and forums like this that allows the greatest airgun minds and the public from all around the world to get together and innovate, exchange ideas and experiences. 

@Cornpone... was your aim at the bullseye in all three cases? If yes, then the 1st group (of random pellets) seems to have a POI to the right at 13mm. The 2nd group (of Yrrah-rolled finalists) seem to have a PPI that was 10mm to the left. And the 3rd group of pellets (that rolled above an below the "finalist group") had a POI 2.55mm to the left. If you lay all three groups' POI over each other, the 1st and 2nd are almost symmetrically opposing the bulls eye and the 3rd group falls right in the middle. Wondering how the rolled pellets that sorted significantly above the "finalists would POI as a group? And also, how the rolled pellets that sorted significantly below the "finalists would POI as a group? 

I wish the distance used for testing would be more than 25m but I understand that you may be limited to what you have available. Pellet weight comes progressively in play at longer distances so at least that's one less variable at 25m.
 
Upvote 0
Ok,

Its all worthwhile I guess, but It didn’t take many of us long to realize we could simply sample the potential pellet designs and weight classes that worked best and then come up with ways to further sort/size/or whatever.

The concept of using the WORST models to do your experiments on IS attractive in that it will likely lead to a less difficult selection of the “best of the worst test cells”. But on a practical level, many would prefer to focus study on one or more of the best grouping designs.

I have tested many, many, pellets each time I try to prepare on a gun for competition, and if i learn of a likely new design, I make ever effort to obtain and test some in several likely guns and compare them with known exemplars.

I tend to do initial testing in my 51 yard test tunnel (which has endured millions of rounds downrange), firing from a decent precision rest on a heavy concrete bench securely fastened to the floor. I typically do a visual inspection for defects, then weigh sort each sample into about five weight samples. I then testfire the three largest weight samples on target, usually three to five five shot groups tells a good story.

Long ago I was critical of the “roll sort” method because head dia variation CAN skew results. It was suggested that Sizing the heads would allow sampling fo just skirt dia variations, but most of my particular guns shoot worse when either heads or both head and skirt are sized.

I have, on several occasions “rolled” the weighed samples of decent shooting pellets, and the test fired samples from the roll test that differed (according to the roll test). I saw no marked grouping or poi differences in the various roll groups.

Typical test groups of good pellet batches in my guns at 51 yards are less than 1moa, with visual and weigh sorted batches being only slightly better by weeding out around 5 to 7 fliers per hundred. 

After testing in the tunnel, I typically do alot more testing at 50yards off the bench outdoors, and sadly, sometime eliminate candidates that were great in the tunnel because they were to susceptible in winds. I normally test known good against the new candidates side by side to better consider wind effects.

And lately, I often shoot in the wind at 100 or more yards just to see.

Once a good brand/model has been test as above, I usually just batch sample new lots outdoors at 50 yards, saving tins tha had good sample results for match shooting.

Typical decent sporting airguns usually deliver 3-5 moa with decent ammo as recommended by the industry. None of the testing mentioned would be important if we are only able of accept normal accuracy and precision of pellets and airguns as the are intended to be used.
























 
Upvote 0
Cornpone,

this is the kind of testing that will move our sport forward. Thank you for taking the time and brains to do it — and share your results with us. 👍🏼👍🏼





Therealld,

what you are doing to test pellets is simply amazing — very cool. 51y tunnel and all.... 👍🏼👍🏼

Now, you mention something that has me puzzled: That pellets that have shown to be well suited to the barrel (small groups) in no-wind conditions perform badly in windy conditions.



I assume that we are comparing the performance of pellets that have a similar BC — maybe you can confirm or disconfirm that. (Comparing a wadcutter with a dome at 51y in the wind isn't much of a fair comparsion.)



Not to derail the thread, I started a new thread asking WHY this can happen. It just puzzles me....

Link: https://www.airgunnation.com/topic/%e2%9d%93-suited-for-the-barrel-pellets-perform-badly-in-the-wind-why-how/



Thanks! 😊

Matthias
 
Upvote 0
I thank fe7565 and boscoebrea for their positive comments. ... I think CORNPONE is on the right track to find objective support (or otherwise) for my system. He has made a good start with his approach already. . .... please enjoy your objective testing and experimenting CORNPONE. ... Best regards to all, Harry (Yrrah in Australia). Am 84 yrs now, have had my two Virus jabs with no problems; and am still experimenting and enjoying all my shooting and sharing on a more limited one-on-one basis with likeminded friends widely separated in countries around our world.
Click to expand...


Thank you, sir. You are a legend.

I hope I can get you some real truth. I do think I am going to have to take this test indoors to get numbers which can be relied upon. Mentioned above a 1mph wind at 25 meters shooting the pellet I am using at 688 fps, chairgun tells me the drift for a full value wind is 3mm. That makes light and variable winds enough to really confuse the data. I have no idea how this is going to turn out.
 
Upvote 0
Ok,
[Good sound reasoning, only removed to reduce the thread size]

I tend to do initial testing in my 51 yard test tunnel (which has endured millions of rounds downrange), firing from a decent precision rest on a heavy concrete bench securely fastened to the floor. I typically do a visual inspection for defects, then weigh sort each sample into about five weight samples. I then testfire the three largest weight samples on target, usually three to five five shot groups tells a good story.

Long ago I was critical of the “roll sort” method because head dia variation CAN skew results. It was suggested that Sizing the heads would allow sampling fo just skirt dia variations, but most of my particular guns shoot worse when either heads or both head and skirt are sized.

I have, on several occasions “rolled” the weighed samples of decent shooting pellets, and the test fired samples from the roll test that differed (according to the roll test). I saw no marked grouping or poi differences in the various roll groups.

Typical test groups of good pellet batches in my guns at 51 yards are less than 1moa, with visual and weigh sorted batches being only slightly better by weeding out around 5 to 7 fliers per hundred. 
Click to expand...

On the number of weight groups: I am sorting into seven groups but I am seeing that probably 99% of the pellets fall into only five of the cells. I could print a catchbox with smaller cells but cell width would start to influence accuracy with pellets bouncing off the sides of the cells and landing in the wrong box. Agreed that five cells should be enough to answer the question we are asking.

I wish I had a setup like you have but the best I can do is 25 yards in a basement. That will probably be enough. 

No question that three to five, five shot groups will usually give you a good idea what a pellet is going to do. That is why I shoot six, five shot groups. Now I toss the five worst shots in the aggregate to help to eliminate fliers due to poor wind doping on my part. I am sure you know wind drift at AG velocities is a real bugger when we are working with millimeter variances. Again I think that calls for an indoor range.

Yes I agree that the roll test selects pellets with a certain head to skirt diameter ratio. I don't know what that means at the target. We might find, as you have experienced, that rolling does not meaningfully separate out similar pellets. I am hoping that I can get meaningful numbers so that we can put the question to bed. It would be very nice to shooters of more modest means than ourselves to discover a simple (and efficient time wise) means to select/group pellets which have a similar POI.

With respect to sizing, I have found that sizing diameter is as critical as pellet selection. Once I have found a pellet which performs well in a rifle, then I start sizing the pellets. In my case both of my Diana spring .22s shoot .217 sized H&N FTTs better than the same pellet from the tin and they shoot H&N FTTs better than any other pellet (most batches anyway). I finally settled on getting that particular pellet in 5.53mm and just shooting those. I think the guns swage them down and they shoot just fine out of the tin. That's the end goal and I think (truth be known) the best advice we can give someone looking for better accuracy after pellet selection is simply to buy that pellet in various head sizes AND figure out which head size shoots best for them. That can be done, of course, by buying a tin and sorting the pellets in that particular tin by head size. Then all the shooter needs do is look for that pellet in the head size which shoots best for him. It's old school but it has a long history of working.

Agreed. Good pellets straight from the tin often shoot to around an MOA in my best shooting springers at 25 yards or so. Other, usually more powerful, rifles won't group as well.

After testing in the tunnel, I typically do alot more testing at 50yards off the bench outdoors, and sadly, sometime eliminate candidates that were great in the tunnel because they were to susceptible in winds. I normally test known good against the new candidates side by side to better consider wind effects.

And lately, I often shoot in the wind at 100 or more yards just to see.

Once a good brand/model has been test as above, I usually just batch sample new lots outdoors at 50 yards, saving tins tha had good sample results for match shooting.

Typical decent sporting airguns usually deliver 3-5 moa with decent ammo as recommended by the industry. None of the testing mentioned would be important if we are only able of accept normal accuracy and precision of pellets and airguns as the are intended to be used.

Click to expand...

Understood that you may well find pellets which shoot well in zero wind but do not perform as well in wind as a lesser pellet (meaning one that does not match it in still air).

Shooting at 100 yards out doors bears little resemblance to the shooting probably 90% plus the average air gunner does. I am him. The longest shot I ever took on game (with an AG) was a squirrel at 78 yards with a D48. It was probably irresponsible to take it but I wanted to show off what my D48 mounting an ATN X-Sight could do with WalMart pellets. It was a kill. The video used to be on YouTube. That's really stretching it for ANYONE shooting pellets in a spring rifle at living targets.

I don't know what the industry recommends but I'd be grateful for a link to that information. I have observed that a well tuned spring rifle with a pellet it prefers will generally shoot between 1.5 and 2.5 MOA at 25 yards on a calm day. Most hunters can't do that in hunting conditions. I have the good fortune to own three untuned rifles that will do that, two D430Ls and an HW98.

Testing for accuracy which can not be practically achieved today informs our decisions for tomorrow. It is always important.
 
Upvote 0
I thank fe7565 and boscoebrea for their positive comments. ... I think CORNPONE is on the right track to find objective support (or otherwise) for my system. He has made a good start with his approach already. . .... please enjoy your objective testing and experimenting CORNPONE. ... Best regards to all, Harry (Yrrah in Australia). Am 84 yrs now, have had my two Virus jabs with no problems; and am still experimenting and enjoying all my shooting and sharing on a more limited one-on-one basis with likeminded friends widely separated in countries around our world.
Click to expand...


Thank you, sir. You are a legend.

I hope I can get you some real truth. I do think I am going to have to take this test indoors to get numbers which can be relied upon. Mentioned above a 1mph wind at 25 meters shooting the pellet I am using at 688 fps, chairgun tells me the drift for a full value wind is 3mm. That makes light and variable winds enough to really confuse the data. I have no idea how this is going to turn out.
Click to expand...

THERE is the issue. Hope you can get some fully controlled (indoor) testing done to further the information but it seems most airgun shooting is still done outdoors so..... Glad to see yrrah (Harry) is healthy at 84.
 
Upvote 0
I thank fe7565 and boscoebrea for their positive comments. ... I think CORNPONE is on the right track to find objective support (or otherwise) for my system. He has made a good start with his approach already. . .... please enjoy your objective testing and experimenting CORNPONE. ... Best regards to all, Harry (Yrrah in Australia). Am 84 yrs now, have had my two Virus jabs with no problems; and am still experimenting and enjoying all my shooting and sharing on a more limited one-on-one basis with likeminded friends widely separated in countries around our world.
Click to expand...


Thank you, sir. You are a legend.

I hope I can get you some real truth. I do think I am going to have to take this test indoors to get numbers which can be relied upon. Mentioned above a 1mph wind at 25 meters shooting the pellet I am using at 688 fps, chairgun tells me the drift for a full value wind is 3mm. That makes light and variable winds enough to really confuse the data. I have no idea how this is going to turn out.
Click to expand...

THERE is the issue. Hope you can get some fully controlled (indoor) testing done to further the information but it seems most airgun shooting is still done outdoors so..... Glad to see yrrah (Harry) is healthy at 84.
Click to expand...


If all goes perfectly I have all day scheduled for an indoor 25 yard range, wed. I'll be the only shooter.

It is good to see Harry is still pushing forward, in spite of China, yes.

I believe the first contact I ever had with him was back when Gene was still running GTA. That's been a while.
 
Upvote 0
Ive rolled a few in my shooting....

I wieghed all mine FIRST into groups then rolled the groups. I wound up with a handful of wieght groups and rolled the biggest two of those. 

Also now of the opinion a head size gauge will be better than rolling. 

Harry AND LD in the same thread. ITs a good day to be on AGN!!



Click to expand...


Tomorrow I will probably collect enough data to confirm your suspicions. Either way I will try to be objective. I'd like for it to be conclusive one way or the other so that is going to involve a few hundred pellets. I guess I should be about making up a target designed for the test.

Yes it IS very good to see such old familiar faces. It pleases me no end to have them commenting with their expertise here.
 
Upvote 0
I believe that it is just about time for me to actually codify all of this information into a white paper with the appropriate statistics and documentation. I'll include an explanation of the geometry, what properties to look for in a good rolling table design, and information about what rolling does NOT measure (weight for example). I will do the math and I will rewrite the five parts you can find here and codify all the information in a PDF which I will make sure is available to anyone who wants it.




 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu